Rivers, canals, estuaries and other water bodies which are used as sources of clean water in developing countries have become polluted by indiscriminate discharge of industrial and animal waste products and by natural processes such as geochemical processes which have introduced dangerous elements including arsenic into the groundwater. Wastewater generated by increasing population, industry and other sources has become problematic in developed countries as well.
Coagulation is an important reaction for water treatment. Ions from heavy metals, as an example, and colloids generally remain in solution as a result of their electric charge. By adding ions having opposite charges to the colloids, the ions and colloids can be destabilized and coagulation can be achieved by chemical or electrical methods. In the case of chemical coagulation, a coagulant, such as Alum [Al2(SO4)3.18H2O] or ferric chloride, as examples, may be employed. However, chemical coagulation tends to generate large volumes of sludge with significant bound water content.
In electrocoagulation, reactive ions may be generated in situ by oxidation of an effective anode material, or reactive metallic hydroxides may be generated within the effluent, and offers an alternative to the addition of metal salts, polymers or polyelectrolytes. Treatment of wastewater by electrocoagulation has been practiced for about 100 years and currently used in many industries. Metals, colloidal solids and suspended particles and oil droplets may be removed from wastewater by agglomeration or coagulation and resultant separation from the aqueous phase. An electrocoagulated floc tends to contain less water, and is more readily filterable.
Basically, an electrocoagulation reactor includes pairs of parallel conductive metal plates, known as sacrificial electrodes which may be of the same or of different materials. When connected to an external source of electrical power, the anode material will electrochemically corrode, while the cathode will be subject to passivation. Metals such as aluminum and iron are commonly used to generate ions in the water which, as stated hereinabove, remove the contaminants by chemical reaction and precipitation, or by causing colloidal materials to coalesce making these species less soluble.
It is known that electrodes in electrocoagulation reactors often experience scaling or other metal coating processes over time which diminish their effectiveness as electrodes, thereby necessitating the use of readily removable and resurfaceable structures.
A Tesla pump includes a plurality of parallel, flat rigid disks having a suitable diameter and keyed to a shaft driven by a motor such that the disks may rotate together as the shaft is rotated. Fluid is caused to enter the pump in the vicinity of the shaft, and liquid adhesion and viscosity directs the fluid toward the periphery as the disks are rotated, thereby imparting energy thereto as the fluid exits the apparatus.